Electronic device adapted to produce high voltage-pulses, especially for igniting a gas lighter

ABSTRACT

The device has a burner, a spark-gap in the vicinity of the burner and an electrical energy supply source. It also includes a switch, time delay means with low consumption of electrical energy adapted to deliver a signal during a time at most equal to a given time when said switch means are in a predetermined position, and amplifier means adapted to amplify the signal supplied by the time delay means. The output signal from the amplifier means supplies oscillator means, and the output signal of the oscillator means supplies voltage raising means, which delivers a signal adapted to actuate the spark-gap.

United States Patent Courier de Mere ELECTRONIC DEVICE ADAPTED TO PRODUCE HIGH VOLTAGE-PULSES, ESPECIALLY FOR IGNlTlNG A GAS LIGHTER Inventor: Henri Edouard Francois Marie Courier de Mere, Paris, France Assignee: Bieosa-Societe de Recherches, Clichy (Haut-deSeine), France Filed: Jan. 22, 1973 Appl No; 325,891

Foreign Application Priority Data References Cited UNITED STATES PATENTS Dietz 431/264 X 1 1 May 13, 1975 Primary E.tuminerEdward G. Favors Attorney, Agent or Firm-Michael S. Striker [57] ABSTRACT The device has a burner, a spark-gap in the vicinity of the burner and an electrical energy supply source. It also includes a switch, time delay means with low consumption of electrical energy adapted to deliver a sig nal during a time at most equal to a given time when said switch means are in a predetermined position and amplifier means adapted to amplify the signal supplied by the time delay means. The output signal from the amplifier means supplies oscillator means, and the output signal of the oscillator means supplies voltage raising means, which delivers a signal adapted to actuate the spark-gap.

31 Claims 9 Drawing Figures .QQN M vu F m g Wm C QI wm x wmwx EL 9mm swm I lllm SHEET 3 BF 5 mmw @m gm mum mm I: m Mu F qmw jwmm 375N755 my 1 3 i9 5 mm 5 W I Km 3w m J 5E R W MN M W Fl. 9W F ELECTRONIC DEVICE ADAPTED TO PRODUCE HIGH VOLTAGE-PULSES, ESPECIALLY FOR IGNITING A GAS LIGHTER The present invention relates to improvements in or to devices for producing high voltage pulses and it relates more particularly to an electronic ignition device comprising a sparkgap for the production of sparks between its terminals and a source for supplying electrical energy, this device being provided for the ignition of a fuel gas, especially for cigarette lighters or gas lighters which comprise suc'h improved electronic gas ignition devices and in which the spark-gap is arranged in the vicinity of the burner.

ln known devices of this type, such as described, for example, in French patent No. l.392,983. the same capacitor is charged and discharged. These devices therefore generally require high voltage batteries having a troublesome bulk and they consume, in operation. a considerable amount of electrical energy, which causes rapid discharge of the one or more batteries. Moreover, the capacitor of these devices also has a considerable bulk and (let rriorates rapidly.

There is also known (French patent No. l,595,998) a device for igniting a flame in apparatus heated by means of gaseous or liquid fuels in which the DC. voltage from a battery is converted directly into alternating current by means of a transistor oscillator In this known device, the periodic signal obtained is applied to the terminals of the primary transformer. The signal which appears at the terminals of the secondary of the transformer is rectified and charges a capacitor which is discharged, as soon as its voltage has reached a given value, through a discharge lamp or the like, into the primary of a second transformer, sparkgaps being arranged at the terminals of the secondary of this second transformer. When the switch of this device is in the on position, said device is constantly energised and thus the consumption of electrical energy is consider able and in this case also the battery therefore discharges rapidly. Moreover, the bulk presented by these devices is considerable and its elements can also dcteri orate rapidly.

It is an object of the invention to overcome the abovementioned drawbacks and especially to enable the production of an electronic ignition device for a cigarette lighter or a gas lighter which requires only one low voltage source of energy and in which the energy used to produce sparks represents the major part of en ergy delivered by the supply source of electrical en ergy. It is another object of the invention to enable the production of such a device which is of reduced size.

Another object of the invention is to provide a device of the type concerned wherein the majority of the electrical circuit elements can be produced in the form of an integrated circuit.

Yet another object of the invention is to enable the production of an improved cigarette lighter comprising such an ignition device,

The electronic ignition device for a fuel gas, especially for a cigarette lighter. according to the invention is characterised by the face that it comprises, in combination:

switch means,

time delay means with a low consumption of electrical energy and adapted to deliver a signal for a time at fit) most equal to a given time when the commutator means are in a predetermined position.

amplifier means adapted to amplify the signal provided by the time delay means,

oscillator means supplied by the output signal of the amplifier means. and

voltage raising means supplied by the output signal of the oscillator means and adapted to deliver a signal suitable for actuating the abovesaid spark-gap.

In a preferred embodiment of the invention, the voltage raising means includes an inductance whose overvoltage coefficient is high. this inductance being advantageously produced in the form of a coil wound on a ferrite core.

In another embodiment, the voltage raising means includes a first transformer.

In a first electronic ignition device according to the invention, the time delay means comprise a first capacitor and, in this case, the switch means comprise at least two positions; said electronic ignition device comprises, in addition, means for charging this first capacitor by a source of electrical energy supply when the switch means are in a first position and means adapted to discharge the first capacitor for a given time when the switch means are in a second position, the amplifier means being adapted to amplify the discharge signal from the first capacitor.

In a second embodiment of an electronic ignition device according to the invention. the time delay means comprise, on one hand, pulse generator means adapted to generate a pulse of a given polarity at the end of a time at most equal to the given time after the switch means have been placed in said predetermined position and, on the other hand. means of the thyristor type comprising a control input connected to the output of said pulse generator means and an output adapted to deiiver the signal before being amplified by the amplifier means, said means of the thyristor type being arranged so as to enable the production of a signal on the input of the amplifier means soon as the commutator means are placed in said predetermined position and to prevent the provision of the said signal to the input of the amplifier means as soon as a pulse of given polarity appears at the control input of said means of the thy ristor type.

Advantageously, in these devices, the amplifier means and the oscillator means comprise, each, a transistor, the amplifier means being adapted to apply their output signal to the base of the transistor oscillator means so as to trigger the latter means and, in this case, if the voltage raising means are constituted by an inductancc with a high overvoltage coefficient, the latter is preferably installed in the circuit of the collector of the transistor of the oscillator means.

Preferably, in this case, said transistors of the oscillator means and of the amplifier means are of opposite type of conductivity and the collector of the transistor of the oscillator means is connected to the base of the transistor of the amplifier means through an impedance of high value.

The device according to the invention comprises. in addition, advantageously,

a second capacitor.

means for charging this second capacitor by the signal delivered by the voltage raising means, these means for charging the second capacitor being such that, at the end of the said given time, the charging voltage of this second capacitor is at least equal to a considerable fraction of its maximum charging voltage.

triggering means comprising. preferably. a thyristor and a second transformer.

the abovesaid second capacitor. triggering means and second transformer being arranged so that the triggering means enable the discharge of this second capacitor into the primary winding ofthe second transformer. the terminals of said sparlcgap being connected to the terminals of the secondary winding of the second transformer. Means for charging the second capacitor are. preferably. arranged to enable the charging of the second capacitor in a time substantially less than the said given time in order that the device may be able to produce at least two sparks during this given time.

In a modification. in which said device also comprises a second capacitor and means for charging this second capacitor by a signal delivered by the voltage raising means. these charging means of the second capacitor being such that. at the end of the given time. the charging voltage of this second capacitor is at least equal to a large fraction of its maximum charging voltage. the discharging circuit of the second capacitor comprises in series a thyristor and the primary winding of a transformer. a Zener diode. whose priming voltage is less than the maximum charging voltage of the second capacitor. it being connected between the anode and the trigger of the thyristor so that its anode is connected to said trigger and its cathode to the anode of said thy ristor. a resistance being in addition provided between the trigger and the cathode of the thyristor.

The source of electrical energy adapted to supply this device may be constituted by a battery with a single element or a rechargeable accumulator.

In another embodiment of the electronic device for igniting a fuel gas. especially for cigarette lighters. according to the invention. the latter is characterised by the fact that it comprises. in combination:

switch means.

time delay means with a low consumption of electrical energy and adapted to deliver a signal fora time at most equal to a given time when the switch means are in a predetermined position.

oscillator means supplied by the output signal of the oscillator means and adapted to deliver a signal adapted to actuate the abovesaid spark-gap.

Other features. characteristics and advantages of the invention will appear below in the course of the more detailed description of preferred embodiments of the invention which follows. with reference to the accom panying drawings. given of course purely by way of illustrative and non-limiting example, in which:

FIG. 1 illustrates a first embodiment of a device according to the invention.

FIG. 2 represents a second embodiment of a device according to the invention.

F103 shows. in part. a third embodiment ofa device according to the invention.

FIG. 4 shows a fourth embodiment of a device ac cording to the invention.

FIGS. 5. f: and 7 each illustrate yet another embodiment of a device according to the invention in which the time delay means comprise means of the thyristor type.

FIG. 8 shows a modification of the electrical energy supply of the device according to the invention and.

FIG. 9 illustrates an embodiment of a cigarette lighter according to the invention.

For simplification. the same reference numerals denote similar elcments in the various Figures.

According to the invention and. more particularly ac cording to those of its types of application as well as according to those embodiments of its various parts to which it would appear that preference should be given. in order to produce an electronic device adapted to It) provide high voltage pulses, especially for the production of sparks for a cigarette lighter or gas lighter. procedure is as follows or in analogous manner.

As is known in itself. such a device provided for the ignition of a combustible gas comprises on one hand.

15 a spark-gap 1 (FIGS. 1, 2. 4, 5, 6 and 7) which can produce sparks between its terminals 2 and 3 and on the other hand. a source of electrical energy supply 4 (FIGS. Ito 7).

According to the invention. there are provided time 20 delay means with a low consumption of electrical energy and switch means 5. The time delay means are arranged to deliver a signal for a time less than a given time when the switch means are in a predetermined position. According to the invention. these time delay 35 means enable the delivery. at most during said given time starting from the moment when the switch means 5 have been placed in said prdetermined position of a signal to the input of the amplifier means which will be considered below.

According to one embodiment of the invention (shown in FIGS. and 4). the device comprises. firstly. switch means 5 with two positions 6 and 7 and a first capacitor 8 forming part of said time delay means. When the switch means 5 are in the first position 6. the 35 source 4 charges the capacitor 8 and when the switch means 5 are in the second position 7, this capacitor 8 discharges over a given time. This device is arranged so that the discharge signal from this capacitor is applied to amplifier means 9'. the signal produced by these amplifier means 9 is applied to oscillator means 10. These oscillator means 10, triggered by said output signal from the amplifier means 9, delivers a high frequency signal to voltage raising means 11. The high frequency signal collected at the output of the voltage raising means 11 is used to actuate the spark-gap 1. Whereas inductor 1] serves as a voltage raising means. it will be understood that the circuit of FIG. I is comprised of components l0, I2, 24. 25, 13 all of which together may be considered a voltage-raising means comprised of an oscillator means 10.

Advantageously and as shown in FIGS. 1, 2, 4, S, 6 and 7, the signal which appears on said output of the voltage raising means It is used to charge a second capacitor 12. this capacitor 12 being arranged in the primary circuit of a second step-up transformer 13. The

latter arrangement is employed of course whatever the embodiment of the circuit adapted to supply the voltage raising mcans I]. Said transformer primary circuit 13 comprises also. trigger means which enable the discharge of the capacitor 12 into the primary winding of this transormer 13. the spark-gap I being. in this case. connected to the terminals of the secondary of the transformer 13. The charging circuit of the capacitor 12 can be arranged so that the charging time of this capacitor is little different preferahly slightly less than the abovesaid given charging time of the capacitor 8. In this case, it is advantageous that at the end of the till said given time the charging voltage of the capacitor 12 be at least equal to a large fraction of its maximum charging voltage, This charging circuit can also be pro vided so that the capacitor 12 is charged in suhstantially less time than said given time so that the device produces several sparks during this given time, in the latter case, the triggering means will be provided to cause the discharge of the capacitor 12 when the latter has reached its maximum charging voltage or a large fraction of the latter.

The switch means 5 with two positions 6 and 7 are, for example. constituted by a double switch which, by its construction, can only occur in a given position (6 or 7) at one time; in other words. when this double switch is in the position 6, the charging circuit of the capacitor 8 is closed and the discharging circuit of this capacitor is open and, conversely, when the said switch is in the position 7, the discharging circuit is closed whilst the charging circuit is open.

There will now be described in detail the embodiment of the invention represented in H6. 1.

Firstly as regards the charging circuit of the capacitor 8, this capacitor is connected directly to the terminals of the source 4 when the switch means 5 are in the position 6. One of the terminals of the capacitor 8 is con nected permanently to the negative pole [-l of said source 4 whilst the other terminal of this capacitor is connected to the positive pole of this source through the first portion of the double switch.

The discharging circuit of the capacitor 8 comprises a resistance whose role is explained below. This resistance 15 is connected on one side, to the positive pole of the source 4 through the first portion 6 of the switch means 5 and on the other side to the base 16 of a transistor 17 of the NPN type of conductivity, this transistor 17 forming part of amplifier means 9.

Oscillator means 10 comprise also a transistor 19 which. itself also, is of the NPN type of conductivity, The voltage raising means It are constituted, in the examples shown in FIG. 1., by a winding 20 having a high overvoltage coefficient. preferably above [00. To this end, the coil 20 is wound on a ferrite core 21.

One terminal of the coil 20 is connected to the collector of the transistor 19 and the other terminal of this coil is connected to the positive terminal of the battery 4. The emitter of the transistor 17 is connected to the base of the transistor 19 through a coil 22 of which the number of turns is greater than that of the coil 20 and which is wound on the same ferrite core 21. This ferrite core 2l has, in the example. the shape of a coil which comprises a central portion of small cross-section. on which are wound the abovesaid windings 20 and 22, and end portions of greater cross-section; in one embodiment, the coil 22 comprises 5 turns and the winding 20 comprises 50. The collector of the transistor 17 is connected to the positive pole of the battery 4. Lastly, the common point to the emitter of the transistor l7 and to the coil 22 is connected to the positive pole of the source 4 through a bypass capacitor 23.

The signal appearing at the terminals of the coil 20 charges the second capacitor [2, a diode 24 retaining the charge of said capacitor. This capacitor 12, which hence charges substantially to the voltage appearing at the terminals of the coil 20, or to a fraction of the latter. is intended. as soon as its charge has reached a given value. to be discharged into the primary of the voltage raising transformer 13 at the terminals of the 6 secondary of which occurs. as has already been indicated above, the spark-gap 1.

To this end. according to another feature of the invention. there is provided in combination a thyristor 25 in series with a primary winding 126 of the transformer 13 in order to close the discharging circuit of the capacitor 12. The trigger 127 of the transistor 25 is in open circuit.

in this device, the discharge of the capacitor 12 is effected automatically when the charging voltage of this capacitor reaches the priming voltage of the thyristor 25. The characteristics of this thyristor 25 will hence have to be selected so that its priming voltage itself corresponds substantially to the desired maximum for the charging voltage of the capacitor 12. In a modification (not shown), the trigger 27 is connected to the cathode of the thyristor 25.

In operation, when the switch 6 is in closed position, the battery 4 charges the capacitor 8. When the switch means are in their second position, corresponding to the closing of the switch 7 and the opening of the switch 6, the capacitor 8 discharges into the base circuit of the 16 of the transistor 17 through the resistance 15. This discharge current amplified by the transistor 17 is transmitted to the base of the transistor [9 through the winding 22 and permits the triggering of the oscillator 10.

The ferrite core 21 has the purpose not only of conferring a high overvoltage coefficient (Q-factor) to the coil 20 but also of constituting a magnetic circuit which enables the transmission to the coil 22 of a fraction of the voltage appearing at the terminals of the coil 20. The coil 22 hence constitutes a feedback coil which contributes to the operation of the oscillator of the circuit of the transistor 19.

To come back to the operation of the supply circuit of the coil 20, it will be noted that when the double switch is tilted into the second position 7. the charging circuit of the capacitor 8 is open and its discharging circuit is closed. The base 16 of the transistor 17 is then connected to the positive terminal of the capacitor 8 through the resistance 15; this transistor 17 hence becomes conductive and, through this fact, the transistor 19 also, since the base of the latter transistor is. under these conditions, connected to the positive pole of the source 4 through the coil 22 and the (low) collectoremitter resistance of the transistor 17 in the conductive state. The capacitor 8 discharges therefore along the following circuit, starting from the positive terminal of the charged capacitor 8: the resistance 15. the baseemitter resistance of the transistor 19 and the switch 7 (closed). The value of the resistance 15 is selected so that it is substantially higher than the sum of the values of the other resistance of the elements which constitute the abovesaid circuit; thus, the discharge time of the capacitor 8. which is approximately equal to the time constant of the discharge circuit, has therefore substan tially the value of the product of the capacity C of the capacitor 8 and the value R of the resistance 15.

It is important to note that the discharge signal of the capacitor 8 is amplified a first time by the amplifier means 9 constituted by the transistor 17 and this amplifier signal applied to the base of the transistor 19 is transformed into an alternating signal (preferably of high frequency) of further increased amplitude due to the Winding 20 with a large overvoltage coefficient. The high frequency signal obtained at the terminals of the winding 20 starts to appear as soon as the double switch is in the position 7 and disappears after the abovesaid given time, determined. as has been seen above, by the time constant RC.

FIG. 2 illustrates another embodiment of the invention in which the voltage raising means are, in the case of HO 1, constituted by an inductance 20 with high overvoltage coefficient, advantageously at least equal to I00. The device shown in FIG. 2 is distinguished from that shown in FIG. 1 by a different arrangement. simpler. of the amplifier means and of the oscillator means. This embodiment according to FIG. 2 enables. as will be seen below, the reduction of the number of elements of the device which do not lend themselves to manufacture in the form of an integrated circuit. In addition, the device constructed according to FIG. 2 enables further reduction of the leakage currents and, hence maximum economisation of the charge of the battery 4, that is to say prolongation of its life.

In the embodiment of the invention shown in this FIG 2, there are also provided trigger means for the discharge of the second capacitor 12 which is different from those shown in FIG. 1.

This device comprises. like that shown in FIG. 1, a charging circuit for the capacitor 8, switch means with two positions, 6 and 7 respectively, a discharge circuit for the capacitor 8 comprising the resistance 15. The position 6 of the switch means corresponds to the closing of the charging circuit of the capacitor 8 and the position 7 of these switch means corresponds to the closing of the discharging circuit of the capacitor 8.

The amplifier means comprise a transistor 120 of the PNP conductivity type and the oscillator means comprise a transistor 12! of the opposite type of conductivity, namely NPN type. The collector of the transistor 120 is connected to the negative terminal of the source 4 through a resistance 122 and its emitter is connected directly to the positive terminal of this source. In addition, the collector of this transistor 120 is connected to the base of the transistor 121. The collector of the transistor 121 is connected to the emitter of the transistor 120 through the coil and its emitter is connected directly to the negative pole of the source 4. A resistance 123 of high value is arranged between the collector of the transistor 121 and the base of the transistor 120.

As shown (and as already mentioned), switch means 5 are arranged so that, when the switch 6 is closed, the switch 7 is open and reciprocally.

In operation, when the switch 6 is closed. the capacitor 8 charges. When the capacitor 8 is charged, switch means are placed in their reverse position, that is to say the switch 7 is closed. The discharge circuit of the capacitor 11 comprises, starting from the positive terminal of this capacitor: the emitter-base junction of the transistor 120, the resistance 15 and the switch 7. The discharge current from the capacitor 8 is amplified by the transistor amplifier means 120 and this amplifier discharge current is applied to the base of the transistor 12] of the oscillator means. The transistor 12] is thus saturated and its operation as an oscillator is ensured due to the resistance 123 which brings back the voltage produced on the collector of the transistor 121 to the base of the transistor and, hence. to the base of the transistor 12]. The transistor 120 has hence a double purpose: on one hand, it amplifies the discharge current of the capacitor 8 and, on the other hand, it constitutes the feedback circuit mounted as an oscillator.

It will be noted that the base of the transistor 12] being connected to the negative terminals of the source 1 through the resistance 122, this transistor is normally blocked, which avoids a superfluous consumption of energy from the battery, The high value of the resistance 123 (with respect to the value of the resistance 15) is necessary so that, on one hand, the voltage applied to the base of the transistor is not too great and on the other hand, that the oscillation frequency of the oscillator means has a high value,

In a particular embodiment, the battery 4 delivers a voltage of LS volts, the capacitor 8 has a capacity of 25 p.F, the resistances 15, 122 and 123 have, respectively, as values 20 KO, 300 Q and 200 K!) and the inductance 20 has the value of 300 p.11, this inductance having a resistance value of the order of 2 Q (measured by DC. current).

As in the case of FIG. 1, the output signal from the transistor oscillator 121 charges the second capacitor 12, this charge being made possible by the presence of the diode 24. There is provided, also, in combination, a thyristor 25 in series with the primary winding of the transformer 13 in order to close the discharge circuit of the capacitor 12 and a Zener diode 26 of which the anode is connected to the trigger of the thyristor 25 and of which the cathode is connected to the common terminal of the capacitor 12 and to the anode of the thyristor 25', in addition, the resistance 27 is connected between the trigger and the cathode of the thyristor 25.

This arrangement of the discharge circuit of the capacitor l2 enables the thyristor 25 to be rendered conductive for a well-determined charging voltage of the capacitor 12 or, in other words, to obtain the discharge of this capacitor 12 into the primary of the transformer 13 from a well-determined value of its charge. Applicant has in fact noted that the voltage itself of triggering the thyristors was generally variable from one thyristor to another whilst with this arrangement, by using a Zener diode, this disparity in the abovesaid values was overcome, given that the voltage from which the capacitor 12 discharges is determined as a function of the priming voltage of a Zener diode whose value is, by definition, well-determined.

The resistance 27 has of course, the purpose of connecting the anode of the Zener diode 26 to the negative terminal of the capacitor 12. This Zener diode, in order that it may be conductive, must have a priming voltage less than the maximum charging voltage of the capacitor 12.

In a modification (not shown), the primary of the second transformer 13 is constituted by the coil 20. In another modification (not shown) there is provided a diode whose anode is connected to the trigger of the thyristor 25 and whose cathode is connected (possibly through a current limiting resistance) to the terminal of the resistance 15 which is not connected to the base of the transistor 120. With this latter arrangement, as soon as the thyristor 25 has passed to the conductive state, the positive pulse is transmitted to the base of the transistor 120, which blocks the latter. The discharge of the capacitor 8 will only continue when the thyristor 25 has returned to the blocked state, that is to say after the production of a spark at the terminals of the sparkgap 1. There are thus obtained sparks of constant energy which can reach high values.

of the transistor 12] There is shown in FIG. 3, yet another embodiment of the part of the device according to the invention which enables the provision of an alternating signal at the terminals of the coil 20 with a high overvoltage coefficient. This embodiment enables further reduction of the number of elements of the device which cannot be realised in the form of a integrated circuit. Moreover. the consumption of electrical energy of this device is reduced to the maximum. as in the embodiment shown in FIG. 3, when the switch 4 is kept closed and the ca pacitor 2 is discharged.

There has been shown in FIG. 3, the part of the device which starting from the signal appearing at the terminals of the coil 20. enables the production of sparks at the terminals of the spark-gap. This portion of the circuit can be formed in any known manner, but preferably according to the embodiment shown in FIG. 2.

In the embodiment of the device according to the invention which is shown in FIG. 3. the resistance of the discharge circuit of the capacitor 8 is constituted by the input impedance of a field-effect transistor 30 (FET). In the Example. this FET transistor is of the N channel MOS type. The input impedance of such a field-effect transistor 30 being high. there may be used a capacitor 8 of sufficiently low capacity for it to be producable as an element of an integrated circuit. If for example said input impedance has a value of 10Q and if there is desired a discharge time for the condensor 8 of 0.5 second. the capacity of this capacitor 8 will have the value of picofarads; such a capacitor is easily manufactured by integration.

The gate 31 of the FET transistor 30 is connected to the terminal of the capacitor 8 through the switch 7. The source 32 is connected to the positive pole of the battery 4 and the drain 33 from this FET transistor 30 is connected to the base of the NPN type transistor 120a forming part of the amplifier means.

The oscillator means of this device comprise also a transistor 121a of the PNP type. A capacitor 123a of low capacity connects the collector of said transistor [21a to the base of the transistor I20u. The capacity of the capacitor 123a is at most equal to 30 picofarads. preferably equal to picofarads. so that the latter is also producable by integration. Generally it is preferred however to use a resistance of high value which is more easily integratable.

Apart from the fact that. with this embodiment of the invention (shown in FIG. 3), the capacitor 8 can be formed as an element of an integrated circuit. it should be noted that the FET transistor 30 constitutes an addi tional amplifying stage. In a general way. the greater the number of amplifying stages. the more the capacity of the capacitor 8 may be selected at a low value.

As regards the embodiment shown in FIGS. 2 and 3, it should be noted that the impedances 123 or 123a are resistive impedances and/or capacitive impedances of high value. In other words. in the case of FIG. 2 there could have been chosen. in place of the resistance [23. a capacitor of low capacity; in the same way in the case of FIG. 3. there could have been selected, in place of the capacitor 123a a resistance of high value.

The operation of the device shown in FIG. 3 is substantially the same as that of the device shown in FIG. 2.

There will now be described, with relation to FIG. 4, another embodiment of the device according to the invention this device shown in FIG. 4 is distinguished from those shown in FIGS. 1 to 3 by a different realisation of the voltage raising means.

In this embodiment. the abovesaid voltage raising means are constituted by a transformer comprising two primary coils respectively 20a and 22a and a secondary coil 20!).

As in the embodiment of the invention shown in FIG. I. the amplifying means comprise a transistor 17 and the oscillator means comprise a transistor 19. These two transistors 17 and 19 are of the NPN conductivity type.

The collector of the transistor 17 is connected to the positive pole of the source 4 and. through the coil 20a of the primary of said transformer, to the collector of the transistor 19. The emitter of said transistor 17 is connected to the base of this transistor 19 by means of a second coil 22a of the primary of said transformer.

The emitter of the transistor 19 is connected to the negative pole of the source 4 through the switch 7 of the switch means 5. The emitters of the transistors 17 and 19 are connected to one another by a bypass capacitor 23a.

The transformer is advantageously constituted by a rod of ferrite on which are wound the primary and secondary coils; this ferrite rod has, for example. the shape of an elongated cylinder. In another embodiment of the transformer IIO, the magnetic circuit of this transformer is constituted by a ferrite coil which comprises on one hand. a central portion of low cross section on which the abovesaid primary and secondary windings are wound and on the other hand. end portions of larger cross-section.

The operation of the supply circuit of the primary windings of the transformer [I0 is substantially identical with that of the device described with respect to FIG. 1. This subject therefore will not be further pur sued. However. it should be mentioned that the coil 20a. connected with the secondary winding 20b of the transformer 110. constitutes a resonating circuit by reason of the self and mutual inductances of these windings as well as of the interfering capacities. in parallel with these windings (the interfering capacity of the secondary winding of the transformer I10 playing a proponderant role). This resonating circuit is connected to the base of the transistor 19 through the transistor l7 and the winding 22a; hence one has a high frequency blocking oscillator assembly. It should also be noted that. for reasons of convenience and of construction. the windings 20a and 22a are wound in opposite sense on the rod (or the coil) of ferrite of the transformer 11. It will also be noted that the high frequency signal obtained at the base of the transistor 19 is dephased with respect to the high frequency signal obtained at the collector of the same transistor.

The capacitor 23a has the role of bypassing the high frequency signal obtained at the terminals of the winding 22a so that this signal cannot short-circuit by alternating current. the transistor 17.

As in the embodiment shown in FIGS. 1 and 3, the winding 20a has preferably a high overvoltage coefficient. Thus it is not necessary to obtain a high voltage at the terminals of the secondary of the transformer 110, for this voltage raising transformer to have a high transforming ratio. given that said high overvoltage coefficient of the winding 20a already enables the obtaining of a high voltage at the terminals of the primary of this transformer lIO.

In the same way in the case of FIG. 2. the signal which appears at the terminals of the secondary winding 20b of the transformer H is rectified by means of a diode 24 to charge a second capacitor I2 and there is also provided a thyristor 25. a Zener diode 26 and a resistance 27 mounted the same way as that described with respect to FIG. 2.

There will now be described. with respect to FIGS. 5. 6 and 7, another embodiment of the time delay means which enables recourse to the capacitor 8 to be avoided (often difficult to realise by integration) and makes the production of a switch means simpler.

In the two embodiments of the invention illustrated in FIGS. 5 and 6, said time delay means comprise an element of the thyristor type 200. Le. a bistable circuit stage. This element of the thyristor type 200 comprises. on one hand. a control input 201 and, on the other hand. an output 202. The time delay means comprise also. pulse generator means which generate a pulse at the latest at the end of said given time. after the switch 5 has been closed. the output of these pulse generator means being connected to the input l of the control. of the element of the thyristor type 200. The thyristor type element 200 is an element which. when it does not receive a pulse at its control input 201, enables the production of a signal at the input of the amplifier means. In addition, this element 200. soon as it has received a pulse ofgiven polarity at its control input 201 delivers at its output a signal which is adapted to prevent the supply of a signal to the input of the amplifier means. This situation. that is to say that in which the thyristor type element prevents the provision of a signal to the input of the amplifier means. only lasts as long as the switch 5 is closed. When said switch 5 is opened. the source 4 no longer supplies any energy but. as soon as the switch Sis once more closed. a signal appears at the input of the amplifier means at the most during said given time.

In the embodiment illustrated in FIG. 5, the thyristor type element comprises two transistors 203 and 204 of opposite conductivity types. The transistor 203 is of the PNP type and the transistor 204 of the NPN type. The emitter of the transistor 203 is connected to a terminal of a resistance 205a. the second terminal of this resis tance 2050 being connected to the positive pole of the source 4 through the switch 5. The base of the transistor 203 is connected to the positive pole of the source 4 through a resistance 205, of lower value than that of the resistance 205a [this resistance being able to have moreover. a zero value). and of the switch 5. Moreover. said base of the transistor 203 is connected to the collector of the transistor 204; in the same way. the base of the transistor 204 is connected to the collector of the transistor 203. The emitter of the transistor 204 is connected directly to the base of the transistor 120. The common point of said emitter of the transistor 204 and the base of the transistor 120 (of the amplifier means) is connected to the negative pole of the source 4 through a resistance 206 which advantageously has a high value.

The pulse generator means are constituted. in this ex ample shown in FIG. 5, by oscillator means 210 which are arranged to be supplied by the source 4 when the switch Sis closed. These oscillator means 210 comprise an output 211 connected to the control input 20] of the thyristor type element 200. It should be noted that said input 201 is constituted here by the common point to the collector of the transistor 203 and to the base of the transistor 204. The oscillator means 210 comprise. in the example. on one hand. a crystal oscillator 212 delivering a high frequency signal and on the other hand. a frequency divider 213 whose input is connected to the output of the oscillator 212; the output of this divider 213 constitutes said output 211 of the oscillator means 210. The frequency divider 213. known in itself. provides a signal of which the frequency is a given fraction of the frequency of the signal generated by the oscillator 212. The period of this signal appearing at the output of the divider 2I3 is. for example. of the order of 0.5 second.

The assembly of the elements ofthe circuit shown in FIG. 5. with the exception of course of the source 4. of the switch 5, of the winding 20. the capacitor 12. of the transformer 13, and of the spark-gap l, is thus realisable in the form of an integrated circuit.

In operation. when the switch 5 is open. the assembly of the elements of the circuit are not supplied with electrical energy. When the switch 5 is closed. the transistor 203 is in the blocked state since the resistance 205a having a value higher than that of the resistance 205. the potential of the emitter of this transistor 203 is less than that of its base. For this reason. the base of the transistor 204 is in open circuit as long as no signal appears at the input 201 and the transistor 204 is therefore. also blocked. As a result the base of the transistor is brought to a negative potential and a signal appears at the terminals of the inductance 20. A spark is hence generated (one or a series of sparks) between the electrodes 2 and 3 of the spark-gap 1.

As soon as the positive pulse appears at the input 20] of the thyristor type element 200, the transistor 204 passes to the conductive state and causes the passage to the conductive state of the transistor 203. The potential of the base of the transistor 120 then becomes substantially equal to the potential of its emitter. which involves the blocking of said transistor 120 and hence. the blocking of the transistor [2]. So no spark can any longer appear at the terminals of the spark-gap l. The saturated state of the two transistors 203 and 204 is maintained as long as the switch 5 remains in the closed position. In fact, the oscillator 210 only delivering positive pulses to its output 211, the transistor 204 is maintained in said saturated state.

It should be noted that the values of the resistances 20S, 205a and 206 will be selected so that the intensity of the current which circulates through these resistances is negligible even when the transistors 203 and 204 are saturated and the switch 5 is closed. In the same way. the oscillator 210 will be selected with char acteristics such that its consumption of electrical energy is negligible. In this way. the energy used to produce a spark. or a series of sparks. each time that the switch 5 is closed, is of minor amount. In other words. the energy supplied by the source 4 is essentially used to produce sparks at the terminals 2 and 3 of the spark gap 1, without superfluous consumption of energy.

In the modification (not shown). the transistors 203 and 204 are replaced by a device of the tetrode thyristor type.

In the embodiment of the invention illustrated in FIG. 6, the pulse generator means are constituted by the electronic ignition device itself.

In addition. in this embodiment, the thyristor type element 200 is a Simple thyristor. In this case. the control input is constituted by the trigger of the thyristor and its output 202 which is connected to the negative pole of the source 4 through the resistance 206 of high value-is taken at the cathode of said thyristor. It should be noted that it is advantageous to select for such an element 200, a thyristor with substantially low holding current, in other words, this thyristor must remain conductive even at relatively low current intensities flowing between its anode and its cathode.

Since the pulse generator means are constituted by the electronic ignition device, a connection 230 is es tablished between the trigger of the thyristor and the trigger of the thyristor 200.

As regards the operation of the device shown in FIG. 6, it will be noted that the thyristor 200 shown in FIG. 6 operates in similar manner to the element 200 shown in FIG. 5. In fact, when first the closed position of the switch 5 is established. the thyristor 200 is not conductive (no signal appearing on its trigger), a signal therefore appears at the base of the transistor 120, and, thus the capacitor 12 is charged. As soon as the charge on this capacitor 12 has reached a given value, the Zener diode 26 becomes conductive. in the same way as the thyristor 2S, and said capacitor 12 can hence be discharged into the primary winding of the transformer I3 and thus there appears a spark at the terminals of the sparkgap I. At the same time, the positive discharge pulse is transmitted to the control input (or trigger) 201 of the thyristor 200 due to the connection 230 and, for this reason, this thyristor 200 becomes conductive, which blocks the transistor 120.

It will be noted that the control of the thyristors 25 and 200 is effected through the Zener diode 26.

It should be noted that the capacitor 12 is charged in a given time and that this time is substantially that at the end of which there is produced a spark at the terminals of the spark-gap I.

It is advantageous to provide a resistance 220 in the path of the connection 230 in order to limit the current arriving at the trigger of the thyristor 200.

When a simple connection is established between the trigger of the thyristor 25 and the control input 201 of the thyristor 200, there is only a single spark produced at the terminals of the spark-gap 1. It may be advantageous, to obtain more reliable ignition to produce a train of sparks at the terminals of the spark-gap 1 when the switch 5 is closed. To this end there may be provided a buffer member 240 shown in discontinuous line in FIG. 6. This buffer member 240 is arranged between the trigger of the thyristor 25 and the control input 201 of the element 200 and is arranged to deliver a positive pulse at its output only when it has received a predetermined number of positive pulses n at its input.

The buffer member 240 is, of course, supplied with electrical energy by the source 4 and its consumption is negligible.

As a modification, it may be envisaged, in place of a thyristor, to use an equivalent element, such as a programable unijunctiom" in this case, it is necessary that the control pulse of the trigger be negative.

There will now be described, with respect to FIG. 7, another embodiment of the device according to the invention in which, contrary to the embodiment of the invention shown in FIGS. 1 and 6, there are not provided amplifier means to amplify the signal provided by the time delay means. In this embodiment, the time delay means supply a signal to the oscillator means di rectly.

As shown in this FIG. 7, the time delay means comprise a tctrode thyristor 2000, for example the tetrode thyristor referred to as BRY 46 distributed by the ITT. Company. The control input 2010 of this device 2000 is constituted by the cathode trigger of said tetrode thyristor 200a.

In this example, the voltage raising means are constituted, as in the case of FIG. 4, by a transformer ll0 with two primary windings 20a and 22a. The oscillator means, again as in the case of FIG. 4, comprise a transistor 19a of the NPN conductivity type.

The positive pole of the source 4 is connected to the anode of the tetrode thyristor 2000 through, on one hand, commutator means 5 and on the other hand, a resistance 20512. The said anode is also connected to the anode trigger 250 of said thyristor 200a through a resistance 2050. This anode is also connected electri cally to the base of the transistor 190 through the winding 220. A bypass capacitor 23b is provided at the terminals of the resistance 205)). The emitter of the tran sistor 19a and the cathode of the tetrode thyristor 2000 are connected to the negative pole of the source 4. The collector of the transistor 19a is connected to the positive pole of the source 4 through commutator means 5 and the winding 20a.

As in the device shown in FIG. 6, the trigger of the cathode of the tetrode thyristor 200a is connected to the trigger of the thyristor 25 through a resistance 2200.

This device has the advantage of enabling simplification of the assembly by reason of the elimination of the transistor ofthe amplifier means. However, it should be noted that the consumption of electrical energy can be greater than that of the devices shown in FIGS. 5 and 6. This is why this embodiment is particularly advantageous for the manufacture of table lighters in which a battery of relatively large capacity can be used.

In operation, as soon as the closed position of the switch 5 has been established, the tetrode thrysitor 200a is not conductive and a signal appears therefore at its anode; this signal is transmitted to the base of the transistor 190 by means of the winding 22a. The oscillator means hence supply a signal at their output and thus, there may appear a spark at the terminals of the spark-gap l at the same time as the positive discharge pulse from the capacitor 12 is transmitted to the control input 2010 of the teterode thyristor 2000. The tctrode thyristor 200a hence becomes conductive and, through this fact, enables the transistor 19 to be blocked.

As in the device illustrated in FIG. 6, there may be provided a buffer member (not shown in FIG. 7).

As regards the circuits which, from the output signal of the voltage raising means 11 (FIGS. 1, 2, 5 and 6) or from the transformer (FIGS. 4 and 7), enable the primary of the transformer 13 to be supplied and which comprise a thyristor 25, it will be noted that it is necessary that, after the capacitor has been discharged, the thyristor 25 returns to its unconductive state, To this end, the selection of the elements of the circuit, in particular the capacity of the capacitor I2 and the inductance of the primary winding of the transformer 13. is made is such a way that the rating of the capacitor 12 is not critical or damped.

It will be noted here that said circuit which, from the output voltage of the voltage raising means 11, controls the spark-gap 1, can be produced in various ways, In particular, it could in certain embodiments, connect directly the sparkgap l to said output terminals of the voltage raising means 1]. There can also be envisaged various modifications of the triggering means enabling the discharge of the capacitor 12 into the primary of the transformer 13; thus, when said circuit is produced according to FlGv 4, the trigger 127 or thyristor can be connected to its cathodev The thyristor 25 can also be replaced by a simple switch.

It will be noted that there can also be provided a protector diode (not shown) to protect the thyristor 25.

it should also be noted that the circuits shown can be produced in the form of integrated circuits or of hybrid circuits (circuits in which all the elements are assembled in the same box).

There will now be described with relation to FIG. 8, a modification of the device according to the invention in which the electrical energy supply is not a battery but a rechargeable accumulator 55 of small dimensions. This accumulator is adapted to be recharged. for example, as shown in FIG. 8, by a battery 56 of photoelectric cells through a diode 7. There may, of course. be envisaged other means for recharging the acculator 55 as, for example, a thermocouple (not shown) of which the hot junction would be heated by the flame caused by the ignition device; the latter arrangement is particularly interesting in the case where this ignition device is used to cause the ignition of the flame of an oven or of the like ignited over a long period.

The device adapted to produce the igniting sparks is advantageously applied to the production of gas lighters.

FlG. 9 illustrates such a lighter which comprises a de vice adapted to produce igniting sparks, according to one of those shown in FIGS. 5, 6 or 7. All the elements of this lighter are, in manner known in itself, enclosed in a case 3011 provided with a cover 31a; this lighter is formed in such a way that the opening of the cap 310 actuates the tilting of the switch means 5, these switch means 5 being constantly in the open position when the cap 31a is in closed position. In this example, a pin 5], fast to the cover 310 holds a strip 4, at the end of which is provided a contact 45, spaced from a contact stop 46; when the cap 31a is raised the contact is established between the stop 46 and the contact 45 (the switch 5 is thus closed).

The lighter is also arranged so that the opening of this cap 31:: actuates the escape of the gas contained in a reservoir 3211 through an output nozzle 33a.

In this FIG. 9, the module 35 represents the electrical circuit elements of the device according to the invention.

Such an embodiment is especially advantageous for a pocket lighter, however. to produce a table lighter, the cap 311! is not indispensable.

The advantages of the device for producing high voltage pulses which hasjust been described are numerous. This device lends itself well, in particular, to miniaturisation. The small electrical energy consumption enables only a single battery element to be used also of reduced dimensions.

The device according to the invention can lend itself to numerous applications besides those already mentioned for cigarette lighters or domestic gas lighters. it

can also be used each time that it is desired to obtain high voltage pulses.

As is self-evident and as emerges already from the foregoing, the invention is in no way limited to those of its types of application and embodiments which have been more especially envisaged; it encompasses, on the contrary, all modifications.

I claim:

1. An electronic ignition device for igniting fuel in cigarette lighters, gas burners and other fuelconsuming apparatus of the type provided with a burner unit and a spark gap arranged in proximity to the burner unit, comprising, in combination, a DC voltage source; voltage raising means connected to said source and to said spark gap and operative for generating a spark voltage across said spark gap, said voltage raising means including oscillator means connected to said source and operative for converting the D.C. volt age of said source into an oscillating voltage having a maximum voltage value higher than the voltage value of said DC. voltage; switch means having an activated condition and an unactivated condition, and being operative when activated for initiating operation of said oscillator means to cause said voltage raising means to generate a spark voltage across said spark gap; and terminating means operative when said switch means remains in activated condition for automatically termi nating operation of said oscillator means upon elapse of a predetermined time interval following the initia tion of operation of said oscillator meansv ,2. An arrangement as defined in claim 1, wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition, and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs, wherein said bistable means comprises a thyristor circuit stage comprised of a bistable thyristor element.

3. An arrangement as defined in claim 1, wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition, and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs. wherein said pulse-generating means comprises means operative in response to activation of said switch means for applying to said bistable means a pulse train having a period equal to said prcdeter mined time interval to cause said bistable means to undergo a transition to said second state thereof.

4. An arrangement as defined in claim 1. wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval. and bistable means operative when in a first state for permitting operation ofsaid oscillator means and operative when in a second state for preventing operation of said oscillator means. means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition. and means connecting said pulse'generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivatcd to activated condition again occurs. wherein said pulse-generating means comprises means for generating a pulse each time a spark voltage is generated across said voltage gap so as to thereby generate a pulse train, and frequency divider means having an input connected to receive said pulse train and having an output constituting the output of said pulsc-gcnerating means.

5. An arrangement as defined in claim 1. wherein said terminating means comprises means automatically operative for terminating operation of said oscillator means upon generation of said spark voltage across said spark gap.

6. An arrangement as defined in claim 1, wherein said terminating means comprises means automatically operative for terminating operation of said oscillator means in response to the generation of a predetermined number of successive spark voltages across said spark gap.

7. An arrangement as defined in claim 1.. wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means. means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition. and means connecting said pu]segcnerating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs. wherein said pulse-generating means comprises means for generating said pulse in response to the generation of a predetermined plurality of successive spark voltages across said spark gap.

8. An arrangement as defined in claim 1.. wherein said terminating means includes a timing capacitor, and wherein said switch means comprises means operative when said switch means is in unactivatcd condition for connecting said timing capacitor to said DC. voltage source to charge said capacitor. and means operative when said switch means is in activated condition for up plying the voltage across said timing capacitor to said voltage-raising means to effect operation of said oscillator means until such time as the voltage across said capacitor falls below a predetermined value, and wherein said terminating means further comprises discharging means operative for discharging said timing capacitor when said switch means is in activated condition.

9. An arrangement as defined in claim I.. wherein said voltage-raising means comprises an inductance connected in the oscillator circuit and periodically energized by current controlled by said oscillator.

It). An arrangement as defined in claim 9., wherein said inductance is comprised of a ferrite core and a coil wound on said core.

II. An arrangement defined in claim 9.. wherein the overvoltage coefficient ofsaid inductance is at least I00.

[2. An arrangement as defined in claim 1.. wherein said voltage-raising means comprises a transformer having a primary winding connected in the circuit of said oscillator means and periodically energized by oscillating current controlled by said oscillator means. so as to cause generation of said oscillating voltage across the secondary winding of the transformer. and means connecting said secondary winding to said spark gap.

13. An arrangement as defined in claim 1.. wherein said voltageraising means further comprises a transistor amplifier stage comprised of an amplifier transistor. and wherein said oscillator means comprises a transistor oscillator stage comprised of an oscillator transistor. and means connecting the output of said transistor amplifier stage to the base of said oscillator transistor. and wherein said switch means comprises means operative when said switch means is activated for applying to said transistor amplifier stage a signal which in amplified form is applied by the latter to said base to initiate operation of said oscillator means.

14. An arrangement as defined in claim 13. wherein said voltage-raising means further comprises a high-overvoltagecoefficient inductance connected in the collector circuit of said oscillator transistor and periodically energized by oscillating current.

15. An arrangement as defined in claim 13, wherein said terminating means includes a timing capacitor. and wherein said switch means comprises means operative when said switch means is in unactivated condition for connecting said timing capacitor to said DC. voltage source to charge said capacitor. and means operative when said switch means is in activated condition for applying the voltage across said timing capacitor to the base of said amplifier transistor. and wherein said tcrminating means further comprises discharge resistance means in the circuit formed by said timing capacitor and said amplifier transistor.

16. An arrangement as defined in claim l4., wherein said voltage-raising means further includes another in ductance having a lesser number of turns and connccted in the base circuit of said oscillator transistor.

the two inductances being wound around a common core.

17. An arrangement as defined in claim 8.. wherein said discharging means comprises a field-effect transistor having a drain gatc current path connectable via said switch means to said timing capacitor to provide a path for timing capacitor discharge current. and wherein said voltage-raising means comprises an oscillator transistor and an amplifier transistor electrically interconnected with each other and an inductance in the output circuit of said oscillator transistor. and means connecting an output electrode of said field effect transistor to an input electrode of said amplifier transistor for causing hitter to apply a signal to the base of said oscillator transistor to render said oscillator means operative when said timing capacitor discharges through said drain-gate current path.

18. An arrangement as defined in claim 14., wherein said inductance constitutes the primary winding of a transformer. and wherein said voltageraising means further includes a secondary winding cooperating with said primary winding. and a further winding connected in the base circuit of said oscillator transistor and inductively coupled with said secondary winding so as to act as an additional primary winding of said transformer.

19. An arrangement as defined in claim 1.. wherein said voltageraising means comprises a capacitor. charging means connected to receive said oscillating voltage and operative for applying a charging voltage to said capacitor to charge the latter. a transformer having a secondary winding connected across said spark gap and having a primary winding. an electronic switch connecting together said capacitor and said pri mary winding to form a capacitor discharge path when said electronic switch is conductive, and dischargeinitiating means for automatically effecting capacitor discharge by rendering said electronic switch conductive after a buildup of charge on said capacitor.

20. An arrangement as defined in claim 19., wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of a time interval which is physically independent of the time interval required for said build-up of charge and for said discharge and which furthermore constitutes said predetermined time interval. and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means. means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition. and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs.

21. An arrangement as defined in claim 20, wherein said bistable means comprises a bistable circuit stage including two transistors of opposite conductivity types, each of the two transistors having a base connected to the collector of the other of the two transistors. and said transistors being connected to said oscillator means for permitting and preventing operation of said oscillator means in dependence upon the conduc tivity of said transistors.

22. An arrangement as defined in claim 19.. wherein said predetermined time interval is a multiple of the time interval required for said build-up of charge and for said discharge. whereby a plurality ofspark voltages are generated across said spark gap prior to termination of operation of said oscillator means.

23. An arrangement as defined in claim 19. wherein said predetermined time interval is greater than and physically independent ofthe time interval required for said build-up of charge and for said discharge.

24. An arrangement as defined in claim 19. wherein said charging means comprises a charging rectifier. and wherein said electronic switch is a thyristor.

25. An arrangement as defined in claim 19.. wherein said discharge-initiating means comprises means operative for rendering said electronic switch conductive when the voltage across said capacitor reaches a predc termined value.

26. An arrangement as defined in claim 19.. wherein said electronic switch is a thyristor. and wherein said dischargeinitiating means comprises means for automatically rendering said thyristor conductive when the voltage across said capacitor reaches a predetermined value. and including a Zener diode having a cathode connected to the anode of said thyristor and an anode connected to the gate of said thyristor. and a resistor connected between the gate of said thyristor and the cathode of said thyristor.

27. An arrangement as defined in claim 1.. wherein said source of DC. voltage is a battery.

28. An arrangement as defined in claim 1.. wherein said source ofD.C. voltage is a rechargeable accumulator.

29. An arrangement as defined in claim 28., and further including means for charging said accumulator.

30. An arrangement as defined in claim 2., wherein said bistable thyristor element is a tetrode thyristor.

31. An electronic ignition device for igniting fuel in cigarette lighters. gas burners and other fuelconsuming apparatus of the type provided with a burner unit and a spark gap arranged in proximity to the burner unit. comprising, in combination. a DC. voltage source; voltage raising means connected to said source and to said spark gap and operative for generating a spark voltage across said spark gap, said voltage raising means including oscillator means connected to said source and operative for converting the DC. voltage of said source into an oscillating voltage having a maximum voltage value higher than the voltage value of said DC. voltage; switch means having an activated condition and an unactivated condition. and being op erativc when activated for initiating operation of said oscillator means to cause said voltage raising means to generate a spark voltage across said spark gap; and terminating means automatically operative for terminating operation of said oscillator means upon elapse of a predetermined time interval following the initiation of operation of said oscillator means. 

1. An electronic ignition device for igniting fuel in cigarette lighters, gas burners and other fuel-consuming apparatus of the type provided with a burner unit and a spark gap arranged in proximity to the burner unit, comprising, in combination, a D.C. voltage source; voltage raising means connected to said source and to said spark gap and operative for generating a spark voltage across said spark gap, said voltage raising means including oscillator means connected to said source and operative for converting the D.C. voltage of said source into an oscillating voltage having a maximum voltage value higher than the voltage value of said D.C. voltage; switch means having an activated condition and an unactivated condition, and being operative when activated for initiating operation of said oscillator means to cause said voltage raising means to generate a spark voltage across said spark gap; and terminating means operative when said switch means remains in activated condition for automatically terminating operation of said oscillator means upon elapse of a predetermined time interval following the initiation of operation of said oscillator means.
 2. An arrangement as defined in claim 1, wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated conditIon, and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs, wherein said bistable means comprises a thyristor circuit stage comprised of a bistable thyristor element.
 3. An arrangement as defined in claim 1, wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition, and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs, wherein said pulse-generating means comprises means operative in response to activation of said switch means for applying to said bistable means a pulse train having a period equal to said predetermined time interval to cause said bistable means to undergo a transition to said second state thereof.
 4. An arrangement as defined in claim 1, wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition, and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs, wherein said pulse-generating means comprises means for generating a pulse each time a spark voltage is generated across said voltage gap so as to thereby generate a pulse train, and frequency-divider means having an input connected to receive said pulse train and having an output constituting the output of said pulse-generating means.
 5. An arrangement as defined in claim 1, wherein said terminating means comprises means automatically operative for terminating operation of said oscillator means upon generation of said spark voltage across said spark gap.
 6. An arrangement as defined in claim 1, wherein said terminating means comprises means automatically operative for terminating operation of said oscillator means in response to the generation of a predetermined number of successive spark voltages across said spark gap.
 7. An arrangement as defined in claim 1., wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition, And means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs, wherein said pulse-generating means comprises means for generating said pulse in response to the generation of a predetermined plurality of successive spark voltages across said spark gap.
 8. An arrangement as defined in claim 1., wherein said terminating means includes a timing capacitor, and wherein said switch means comprises means operative when said switch means is in unactivated condition for connecting said timing capacitor to said D.C. voltage source to charge said capacitor, and means operative when said switch means is in activated condition for applying the voltage across said timing capacitor to said voltage-raising means to effect operation of said oscillator means until such time as the voltage across said capacitor falls below a predetermined value, and wherein said terminating means further comprises discharging means operative for discharging said timing capacitor when said switch means is in activated condition.
 9. An arrangement as defined in claim 1., wherein said voltage-raising means comprises an inductance connected in the oscillator circuit and periodically energized by current controlled by said oscillator.
 10. An arrangement as defined in claim 9., wherein said inductance is comprised of a ferrite core and a coil wound on said core.
 11. An arrangement as defined in claim 9., wherein the overvoltage coefficient of said inductance is at least
 100. 12. An arrangement as defined in claim 1., wherein said voltage-raising means comprises a transformer having a primary winding connected in the circuit of said oscillator means and periodically energized by oscillating current controlled by said oscillator means, so as to cause generation of said oscillating voltage across the secondary winding of the transformer, and means connecting said secondary winding to said spark gap.
 13. An arrangement as defined in claim 1., wherein said voltage-raising means further comprises a transistor amplifier stage comprised of an amplifier transistor, and wherein said oscillator means comprises a transistor oscillator stage comprised of an oscillator transistor, and means connecting the output of said transistor amplifier stage to the base of said oscillator transistor, and wherein said switch means comprises means operative when said switch means is activated for applying to said transistor amplifier stage a signal which in amplified form is applied by the latter to said base to initiate operation of said oscillator means.
 14. An arrangement as defined in claim 13, wherein said voltage-raising means further comprises a high-overvoltage-coefficient inductance connected in the collector circuit of said oscillator transistor and periodically energized by oscillating current.
 15. An arrangement as defined in claim 13, wherein said terminating means includes a timing capacitor, and wherein said switch means comprises means operative when said switch means is in unactivated condition for connecting said timing capacitor to said D.C. voltage source to charge said capacitor, and means operative when said switch means is in activated condition for applying the voltage across said timing capacitor to the base of said amplifier transistor, and wherein said terminating means further comprises discharge resistance means in the circuit formed by said timing capacitor and said amplifier transistor.
 16. An arrangement as defined in claim 14., wherein said voltage-raising means further includes another inductance having a lesser number of turns and connected in the base circuit of said oscillator transistor, the two inductances being wound around a common core.
 17. An arrangement as defined in claim 8., wherein said discharging means comprises a field-effect transistor having a drain-gate current path connectable via said switch means to said timing capacitor to provide a path for timing capacitor discharge current, and wherein said voltage-raising means comprises an oscillator transistor and an amplifier transistor electrically interconnected with each other and an inductance in the output circuit of said oscillator transistor, and means connecting an output electrode of said field-effect transistor to an input electrode of said amplifier transistor for causing latter to apply a signal to the base of said oscillator transistor to render said oscillator means operative when said timing capacitor discharges through said drain-gate current path.
 18. An arrangement as defined in claim 14., wherein said inductance constitutes the primary winding of a transformer, and wherein said voltage-raising means further includes a secondary winding cooperating with said primary winding, and a further winding connected in the base circuit of said oscillator transistor and inductively coupled with said secondary winding so as to act as an additional primary winding of said transformer.
 19. An arrangement as defined in claim 1., wherein said voltage-raising means comprises a capacitor, charging means connected to receive said oscillating voltage and operative for applying a charging voltage to said capacitor to charge the latter, a transformer having a secondary winding connected across said spark gap and having a primary winding, an electronic switch connecting together said capacitor and said primary winding to form a capacitor discharge path when said electronic switch is conductive, and discharge-initiating means for automatically effecting capacitor discharge by rendering said electronic switch conductive after a build-up of charge on said capacitor.
 20. An arrangement as defined in claim 19., wherein said terminating means comprises pulse-generating means operative for generating a pulse upon elapse of a time interval which is physically independent of the time interval required for said build-up of charge and for said discharge and which furthermore constitutes said predetermined time interval, and bistable means operative when in a first state for permitting operation of said oscillator means and operative when in a second state for preventing operation of said oscillator means, means connecting said switch means to said bistable means for causing said bistable means to undergo a transition to said first state in response to transitions of said switch means from unactivated to activated condition, and means connecting said pulse-generating means to said bistable means for causing said bistable means to undergo a transition to said second state in response to receipt of said pulse and to remain in said second state until such time as a transition of said switch means from unactivated to activated condition again occurs.
 21. An arrangement as defined in claim 20, wherein said bistable means comprises a bistable circuit stage including two transistors of opposite conductivity types, each of the two transistors having a base connected to the collector of the other of the two transistors, and said transistors being connected to said oscillator means for permitting and preventing operation of said oscillator means in dependence upon the conductivity of said transistors.
 22. An arrangement as defined in claim 19., wherein said predetermined time interval is a multiple of the time interval required for said build-up of charge and for said discharge, whereby a plurality of spark voltages are generated across said spark gap prior to termination of operation of said oscillator means.
 23. An arrangement as defined in claim 19, wherein said predetermined time interval is greater than and physically independent of the time interval required for said build-up of charge and for said discharge.
 24. An arrangement as defined in claim 19, wherein said charging means comprises a charging rectifier, and wheRein said electronic switch is a thyristor.
 25. An arrangement as defined in claim 19., wherein said discharge-initiating means comprises means operative for rendering said electronic switch conductive when the voltage across said capacitor reaches a predetermined value.
 26. An arrangement as defined in claim 19., wherein said electronic switch is a thyristor, and wherein said discharge-initiating means comprises means for automatically rendering said thyristor conductive when the voltage across said capacitor reaches a predetermined value, and including a Zener diode having a cathode connected to the anode of said thyristor and an anode connected to the gate of said thyristor, and a resistor connected between the gate of said thyristor and the cathode of said thyristor.
 27. An arrangement as defined in claim 1., wherein said source of D.C. voltage is a battery.
 28. An arrangement as defined in claim 1., wherein said source of D.C. voltage is a rechargeable accumulator.
 29. An arrangement as defined in claim 28., and further including means for charging said accumulator.
 30. An arrangement as defined in claim 2., wherein said bistable thyristor element is a tetrode thyristor.
 31. An electronic ignition device for igniting fuel in cigarette lighters, gas burners and other fuel-consuming apparatus of the type provided with a burner unit and a spark gap arranged in proximity to the burner unit, comprising, in combination, a D.C. voltage source; voltage raising means connected to said source and to said spark gap and operative for generating a spark voltage across said spark gap, said voltage raising means including oscillator means connected to said source and operative for converting the D.C. voltage of said source into an oscillating voltage having a maximum voltage value higher than the voltage value of said D.C. voltage; switch means having an activated condition and an unactivated condition, and being operative when activated for initiating operation of said oscillator means to cause said voltage raising means to generate a spark voltage across said spark gap; and terminating means automatically operative for terminating operation of said oscillator means upon elapse of a predetermined time interval following the initiation of operation of said oscillator means. 